Joel and Dana of the blog Well Preserved are getting this nose-to-tail eating down to an art form with fruits and vegetables and Joel's dedication (he even scrubs the roots of leeks clean, dries and powders them) has motivated me to find more ways of making something useful out of the trimmings and leftovers from preparing fruits and veg for preserving.
After preparing this year's batch of the greatest tomato paste ever I had a pile of pulp and seeds leftover.
I spread the pulp on dehydrator racks covered with silicone sheets for making fruit leather. I've found plastic wrap spread on the racks works nearly as well as the sheets. If you're doing this in your oven I recommend covering a baking sheet with foil shined with a bare minimum of oil to prevent sticking.
The rack went into the dehydrator set at 135F. If you're using the oven set it at the lowest temperature with the door cracked. I have a terrible habit of just twisting the dehydrator timer on to 6 hours and walking away so I can't give you an exact time for how long the pulp took to dry but it was much less than 6 hours. More like 3-4 hours. But dehydrating isn't an exact science. Variables in humidity, moisture in the fruit or veg, how heavily loaded the dehydrator/oven is, all make an exact time impossible to determine. In this case the pulp was ready when it was crispy dry. Oven dried pulp needs to be watched far more closely because even at low temps it can go from dried to burned. So keep an eye on it and when it's crispy dry, pull it.
You can see that when the pulp was ready it bubbled up and pulled away from the sheet.
I allowed the sheet of pulp to cool to room temperature and then immediately broke it up into small pieces that fit inside my coffee/spice grinder. We've been having a lot of high humidity days here so it was imperative to not let the sheet sit to reabsorb moisture from the air. The grinder made short work of pulverizing the pulp and left me with a very intensely flavored tomato powder. I immediately moved the powder into a clean air tight container for storage. The grinding process kicks up a little heat in the powder which produces a little condensation as it cools. If the powder becomes a little too clumpy spread it out on a baking sheet and place it in a warm oven for just a minute or two. Remove the powder from the oven, pour on a piece of foil and allow it to cool to room temperature (another minute or two). When cool, pour it into an air tight container.
This powder will get stirred into all manner of things: soups, sauces, mayo, bread/biscuit/pasta doughs to name a few. I'm already in the process of drying celery and onions to make a "Holy Trinity" bouillon powder. Last week when sorting through this year's cured garlic the damaged cloves that wouldn't store were blanched, peeled, chopped fine, dried and powdered.
In addition to freezing good bits of veg to flavor liquid stocks with, I'm finding that the dehydrator is an excellent way to convert those bits into pieces and powders that will sit happily on the shelf until needed. Unfortunately, the chickens aren't as pleased as I am.